Page 12 - Wire Bonding in Microelectronics

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8.1.7 Silicon Nodule-Induced
Cratering . . . . . . . . . . . . . . . . . . . . . . . 263
8.1.8 Cratering Over Polysilicon . . . . . . . . 266
8.1.9 Gallium Arsenide Cratering . . . . . . . 266
8.1.10 Conclusions of Cratering . . . . . . . . . 269
8.2 Cracks in the Heels of Ultrasonic
Wedge Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
8.3 The Effect of Acceleration, Vibrations, and
Shock on Open-Cavity Packages . . . . . . . . . . 273
8.3.1 Centrifuge Test for Wire Bond
Reliability on Wire Bonds . . . . . . . . . . 273
8.3.2 The Effect of Ultrasonic Cleaning,
Launch Vehicles Pyro-shocks,
Vibrations, etc., on Open-Cavity-
Package Wire Bonds . . . . . . . . . . . . . . 275
8.3.3 The Effect of Shock and Vibration
Tests on Wire Bonds (Problems with
Long Wires) . . . . . . . . . . . . . . . . . . . . . 278
8.4 Effects of Power and Temperature Cycling
of Wire Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Appendix 8A Fracture Toughness Defi ned Fracture
Toughness is the Stress Required to Extend an
Existing Crack . . . . . . . . . . . . . . . . . . . . . . . . . . 284
Appendix 8B Design of Experiments (DOE) for
Wire Bonder Setup . . . . . . . . . . . . . . . . . . . . . . 284
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
The Math is in the Software, the Value You
Add is Your Engineering Knowledge . . . . . . . 285
What’s a Statistic, Effect, and Interaction . . 285
What is a DOE? . . . . . . . . . . . . . . . . . . . . . . . . 286
Choosing Variables and Ranges . . . . . . . . . . 286
Sequential Experimentation . . . . . . . . . . . . . 288
Process Capability . . . . . . . . . . . . . . . . . . . . . . 288
Experiments to Improve Yield . . . . . . . . . . . 289
Gage R&R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
9 Advanced and Specialized Wire Bonding
Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
9.1 The Technology and Problems of High
Yield and Ever-Finer Pitch Wire Bonding,
and Specialized Looping . . . . . . . . . . . . . . . . . 293
9.1.1 Introduction to High Yield in Modern
Wire Bonding . . . . . . . . . . . . . . . . . . . . 293